Elevator safety apparatus



May 5, 1931. A. MARKS ELEVATOR SAFETY APPARATUS Filed July 5. 1929 2 Sheets-Sheet 1 mm M INVENTOR ATTORNEY M 5, 1931- A. MARKS 1,803,762

ELEVATOR SAFETY APPARATUS Filed July 5. 1929 2 Sheets-Sheet 2 l NVENTOI? ATTORNLY Patented May 5, 1931 UNITED STATES,

PATENT OFFICE MARKS, OF CHICAGO, ILLINOIS, ASSIGNOR T0 OTIS ELEVATOR COMPANY,

OF NEW YORK, N. Y., A. CORPORATION OF NEW JERSEY ELEVATOR SAFETY APPARATUS Application filed July 5,

The invention relates to elevator safety apparatus, particularly to safety ap aratus for stopping the descent of a movable ody in the hatchway of an elevator system when an emergency condition arises.

In the normal operation of an elevator system, the elevator car and counterweight are moved up and down the hatchway, subject to the control of suitable control devices of a nature depending upon the type of system installed. In modern electric elevators, such as those of the traction ty e, the final stop under normal conditions is e ected by applying an electromechanical brake to the hoisting motor. When an emergency arises safety apparatus is brought into operation to act on the movin bodies themselves to bring them to a stop. arious types of safety apparatus have been devised to effect emergency stops, including buffers for stopping the descent ofthe movable bodies at their lower limitof travel and safety brake mechanism, usually arranged to grip the guide rails, for bringing a movable body to a stop during its descent at other points in the hatchway. It is desirable that the safety apparatus effect the stop when an emergency occurs without excessive retardation because of the possibility of damage to the installation and the danger to life and limb of the occupants of the elevator car involved in emergency stops madeat an excessive rate of retardation. It is also desirable that the safety apparatus be brought into operation in the least possible time when an emergency arises, and that the operation of the safety apparatus be uniform over a considerable number of operations.

The object of the present invention is to cause emergency stops to be effected in such manner that the danger of shock or injury to occupants of the elevator car and the possibility of damage to the elevator installation is minimized.

A feature of the present invention is the provision of safety apparatus'which, when brought into operation at the same speed of the descending body, imparts the same average retardationto the body regardless of the total mass to be stopped or the point in the 1929. Serial No. 375,953.

uniform operation is had over a considerable number of operations.

- A fourth feature is the provision of safety apparatus which is reliable in operation, of

simple construction and which may be cheaply manufactured and easily installed.

Other features and advantages will become apparent from consideration of the following description and appended claims.

The invention involves stopping the descent of a movable body of an elevator system by a retarding device, brought into operation when an emergency arises, regardless of the position of the movable body in the hatchway at the time the emergency condition occurs.

In the embodiment of the'invention to be described, a buffer is provided on a movable body of an elevator system. This bufi'er cooperates with a bumper, provided in the elevator it, to retard the sto the descent of the body at its lower limit 0 travel. Safety brake mechanism of a type arranged to grip the guide rails is also provided for the movable body and is carried by the buffer cylinder. The safety brake mechanism is arranged to be operated, as by an overspeed governor, at any pointin the hatchway, depending on the position of the body at the time an emergency condition occurs. Upon operation, the safety brake mechanism grips the guide rails, as the movable body descends, to bring the buffer cylinder to a stop. I The buffer plunger thereupon descends into the buffer cylinder, causing the descending body to be gradually retarded and finally brought to a stop.

In the drawings Fi ure 1 is a schematic representation of an e evator installation showing the safety apparatus applied to both the elevator car and the counterwei ht;

Figure 2 is an en arged view showing the arrangement of the safety apparatus, parts being shown in section to illustrate details of construction;

Figure 3 is a sectional elevation on line 33 of Figure 2 further illustrating the arrangement of the safety a paratus and also showing details of the sa ety brake mechanism;

Figure 4 is a view, partly in section, along line 4-4 of Figure 2 showing operating mechanism for the safety brake;

Figure 5 is a section taken along line 5-5 of Figure 3 showing details of the safety brake mechanism; and

Figure 6 is a section taken along line 66 of Figure 5 further illustrating details of the safety brake mechanism.

Referring to Figure 1, the elevator car 20 and counterweight 21are raised and lowered by the hoisting motor 22. An electromagnetic brake 23 is provided for bringing the hoisting motor, and consequentlv the car and counterweight, to a stop. lhe hoisting ropes 24 for the car and counterweight extend from the top of the elevator car over the hoisting sheave 25 on the motor shaft to the top of the counterweight. Compensating ropes 26 extend downwardly from the bottom 0 the counterweight around the tensioning sheave 29 in the elevator pit and upwardly from this sheave to the bottom of.

the elevator car. The tensioning sheave 29 is arranged so as to be freel movable upwardly and downwardly in guides 28. Guide shoes 40 are provided for the elevator car 20 and cooperate with guide rails 27 in the hatchwa to guidethe car in its movement up and own the hatchway. Similar ide shoes are provided for the counterweig t 21 and cooperate with other guide rails 27 to guide the counterweight in its movement up and down the hatchway. As the safety apparatus for the elevator car is of substantially the same construction as that for the counterweight, only the arrangement of the safety apparatus for the counterweight will be described in detail. Referring to Figures 24, the

pilun er 30 of an oil buifer, desi nated as a w ole y 31,

is provided with a oot plate 32 secured tothe cross member 33 of the counterweight support. Suspension rods 34 depend from the foot late 32 and extend through openings in t e portion 35 of buffer cylinder 36 to suspend thebufier cylinder from foot plate 32 and to guide the plunger-30 in its movement in the cylinder. The cylinder is provided with upper and lower chambers. The upper chamber is provided with bafile plates 37. Longitudinal groves 38 are formed in the surface of plunger 30. The grooves 38 taper gradually from their lower to their upper ends. A non-compressible liquid, such as oil, is placed in the lower chamber of cyljJnder 36 and partially fills the upper cham- Channel members 42 are spaced from safety beams 43 by uprights 44. Plates 45 and 46 mounted on the channel members 42 and safety beams 43, respectively, are provided with openings guiding the buffer cylinder 36. A collar 47 1s formed on the plate 46 and bears against a stop or flange on a cap 48, closing the end of cylinder 36, to normally support the channel members 42 and safety beams 43. Guide shoes 50 are secured to the safety beams 43 and cooperate with the guide rails 27 to guide channel members 42 and safety beams 43 in their movement with the elevator car. A spring 51 is mounted between the plate 45 and the portion 35 of the cylinderand surrounds a collar formed on the plate 45.

A bell crank lever 52, fixed to a rock shaft 53 pivotally mounted 1n the channel members 42, is adapted to be operated to apply the safety brake mechanism hereinafter described in detail. Referring also to Figure 1, a governor rope 59 is secured to a rope socket 54 pivotally connected to one arm 55 of bell crank 52, and extends upwardly in the hatchway over a governor sheave 60, then downwardly around a tension sheave 61, mounted for movement in guides 62, and back to a similar rope socket 63, also pivotally connected to arm 55. The governor rope 59 follows the movement of arm 55 with the counterweight and drives the sheave 60 to operate the governor 64 in accordance with the rate of movement" of the counterweight. The construction of the governor 64 for the counterweight is the same. as that of governor 97 for the car. The details of the governor for the car will be described inasmuch as the details of the governor for the counterweight are not shown. 7 A lever 65, pivotally mounted on the governor frame, is connected to the movable sleeve of governor 97 for movement'therewith. A rod 66 connected to lever is also connected to jaw 57 and is adapted upon movement of the governor sleeve to rock the jaw 57 clockwise about its pivotal support 67. The jaw 58 is connected, as by gearing, to the jaw 57 for movement therewith. The jaw 58 is pivotally mounted on a pin in a yoke on the end of a rod 68 provided with a collar 70. Rod 68 is mounted in bearings 71 and a spring 72 surrounding rod 68 and bearing against the collar on rod 68 and one of the bearings 71 maintains the jaw 58 in operative relationship with the jaw 57. The governor rope 96 for the car extends through guide 56 and between jaws 57 and 58 to be gripped thereby when the nel members 42. A spring 78. surrounding link bears at one end against a stop on link 75 and at its other end against a fixed guide 81 for link 75 to bias the bell crank 55 and lever 76 to the positions illustrated in Figure 2. Levers 83, mounted on rock shafts 53 and77 for movement therewith, are adapted to raise lift rods 84 when shafts 53 and 77 are rocked. The construction of that portion of the safety brake mechanism operated by the lift rods 84 is the same for each guide rail and only one portion will be described in' detail.

Referring to Figures 3, 5 and 6, the lift rod 84 has a flattened portion provided with a cam slot 85 through which .a pin 86 mounted on safety block 87 projects. The safety block 87 is secured between the safety beams 43 and is provided with a guide slot 88 for the-guide rail 27. One side of guide slot 88 is close to and parallel with the guide rail 27 while the other side of slot 88'forms a cam surface 90. An angular projection 91 at the base of the lift rod 84 supports a safety roll 92 between the end of slot 88 and the rear surface of the lift rod 84, the roll 92 being maintained in position on the projection 91 and against the lower end of cam surface by a pin 93 extending from the end wall of the slot 88.

The buffer for the car is designated as a whole by 94 and the safety brake'mechanism forthe car is designated as a whole by 95. Bumpers 98 and 99 are provided in the elevator pit for cooperation with the-buffer cylinders of the car and counterweight respectively to retard and stop the car and counterweight at their lower limits of travel.

The operation is as follows: When theelevator car and counterweight are being driven by the hoisting motor 22, thegovernor 64 for the counterweight is driven through governor rope 59 in accordance with the speed of the counterweight: Upon the occurrence of a predetermined overspeed during the de-- scent of the counterweight, the governor 64 operates to cause its jaws to grip the governor rope! The mot1on of governor rope 59 is thus retarded, and stopped as the counterweight continues to descend, resulting. in

movement of bellcrank 52 to rock'shaft ,53]

directly and shaft 77 through link 75 and lever 76. Rocking movement'of shafts 53 and- 77 operates the'levers 83 to cause lift rods 84 to move upwardly, the pins 86jprojecting from safety blocks 87 cooperating with the I cam slots 85 in lift rods 84 to move the lower descent of cylinder'36 is retarde safety rolls 92 are moved into contact with guide rails 27 the descent of the counterweight along the guide rails causes safety 'rolls to be jammed between the guide rails 27 and the cam surfaces 90 formed on the safety block, resulting in the descent'of safety beams 43 and channel members 42 being retarded and terminated. vWith thisarrange ment, the safety beams 43 move only a very slight distance along the guide rails 27 after movement of governor rope 59 is'retarded upon the operation of governor 64 The momentum of the counterweight causes it to continue to descend, carrying the plunger 30 and buffer cylinder 36 therewith, after channel members 42 and safety beams 43 have been brought to rest by the operation of the safety'brake mechanism. Continued downward motion of the counterweight causes the cylinder 36 to be moved through the plates 45 and 46, compressing the sprin 51 between the ortion 35 of cylinder 36 and the plate 45. spring 51 is com ressed the and then brought to rest on channel members 42'.

The counterweight continues its descent and forces the plunger 30 into the buffer cylinder 36, the plunger being guided by the susnsion rods 34 which move through the cylmder head 35 and between the channel members 42 and safety beams 43. As plunger 30 is forced into cylinder 36, it forces Oll upwardly from the lower chamber through'the grooves 38 into the upper chamber of cylinor 36. Because the grooves 38 taper from a maximum at the lower end of plunger 30 to aminimum near the upper end thereof,

the area of the openings through which the oil may escape from the lower chamber of cylinder 36, is gradually restricted as plunger 30 is forced into the cylinder. As a result, thedescendingmovement of plunger 30, and consequently of the counterweight, is gradually retarded and the counterweight is finally '1 of the car, the governor 97 effects the application of safety brake mechanism 95. It is to be noted that the safety apparatus described causes emergency stops to bemade in the same distance of travel of the descending-body due to the fact that the buffer plunger always moves the same distance in bringin the descending body to a stop.

he bufi'er, upon operation, gradually absorbs the inertia of the descending mass due 5 to the taper of the grooves 38as above described. With such arrangement, the descending body is brought to a stop by the buffer at the same average rate of retardation, regardless of the total mass to be stopped, provided the speed of the descending body is the same when the buffer is brought into operation. The buffer may be designed for various rates of retardation, depending on the requirements of the particular installation.

to give an average retardation of gravity when brought into operation by the trip ing of the governor as the descending ody reaches governor tri ping speed.

sto by the safety apparatus, the ascending b0 y, unless acted upon by some external force such as due to continued rotation of the driving sheave, retards at a. gravity rate.

2 With the buffer arranged to provide average gravity retardation when brought into operation as a resultof the tripping of the ggvernor, the ascending body and descending dy are brought to rest atthe same time.

Thus, with the combined safety brake mechanism and bufler, there is little tendency of the ascending bod to continue its upward movement after the descending body is brought to astop.

Should the ascendin body continue its upward motion after the escending body comes to rest, slack willdevelop in the hoisting ropes, permittingthe ascending body thereafter to fall back. In the event that the rate of descent of the ascending body in falling back exceeds a redetermined speed, the

combined safety br e mechanism and buffer for this body'will function to stop the body, preventin excessive strains being laced upon the oisting ro es with the possi le resultant damage to t e elevator installation and injury to occupants of the elevator car.

It is to be noted that when the safety brake is applied to stop the descent of a moving bod first the safety brake acts to bring safety ams 43 to rest. The descent of the buffer cylinder 36 is then retarded and its momentum absorbed by compression of the spring 51. The safety brake mechanism and guide rails are not required, upon application of the safety brake mechanism, to stand the strain of imtially absorbing the momentum of the relatively large mass of the counterweight or the elevator car, but the momen- 60 tum of the descending mass is gradually absorbed by the operation of the buffer to radually retard the descending mass and l mally bring it to rest. Thus, the possibility of damage to the elevator installation as a result of operation of the safety apparatus A suitable arrangement is to design the bufl'er When the descen ing body is brought toa' is minimized. Furthermore, excessive rates of retardation of the descending body, resulting in discomfort or possible injury to occupants of the car, are prevented. In fact, all the advantages of a buffer stop are had, regardless of the point in the hatchway at which the emergency operation occurs.

It is to be further noted that when the safety rolls are wedged against the guide rails, the beams are brought to rest substan tially instantaneously owing to the fact that the safety beams and channel members constit'ute a relatively small mass to be brought to a stop. Consequently, wear of the parts of the safety brake mechanism, such as the roll and the surfaces of the slot in thesafety block, and gouging of the guide rails is minimize-d, and the safety apparatus may be operated a considerable number of times without replacement.

The arrangement described permits the use of safety brake mechanism of very simple and inexpensive construction such as the safety brake mechanism chosen for purposes of illustration and description. It is to be understood, however, that other types of safety brake mechanisms or other means for causing the operation of the retarding device may be employed.

The safet apparatus as shown is especially suitable fbr the counterweight particularly as the safety brake -me'chanism requires very little space'and as counterweights usually carry buffers to which a'sa-fety brake mechanism may be ap lied. However. the safety apparatus may be applied to either the counterweight or the car, or both of them if desired.

The system may be arranged if desired so that the tensionin sheave for the compensating ropes is tie down either against any upward movement or so as to permit only a limited upward movement thereof, once it has taken a certain position, but is freely movable in the downward direction. In such event, the elevator car, counterweight and roping are caused to function as a closed system during emergency sto s. When an emergency stop occurs, there ore, not only are all the elements of this closed system retarded as a unit but the forces exerted on both the car and the counterweight sides act together on the total mass of the system to effect the retarding action. With the forces combined-in this manner the maximum retardation obtained under various conditions of load is minimized.

The principles of the invention will be understood from the above description of the various devices and parts, together with their arrangement and interrelation. It is to be understood, however, that various changes may be made in details of construction of the various parts, not only with respect to the safety brake mechanism, but also with respect to other parts of the apparatus. For example, other types of buffers or other retarding devices may be employed. Different types of mechanism may be employed to effect the operation of the safety apparatus in the event of overspeed. The operation of the safety apparatus may be efi' ected by other than speed responsive devices, such as means to effect the operation of the safety apparatus in the event of breaking or stretching of one or more of the hoisting ropes. Con-' sequently, it will be understood that all alterations or variations in the construction or interrelation of such parts which do not alter the general principles of operation of the invention may be made Without departing from the scope of the invention. What is claimedis:

1. In an elevator installation, a hatchway, a body movable in said hatchway, guide rails for said bo y, a buffer carried by said body, safety brake mechanism carried by said buffor and adapted upon operation to grip said rails to cause the operation of said buffer to retard and stop the descending of said body, means for causing the operation of said safety brake mechanism at any point in the hatchway, and resilient means surrounding a portion of said buffer for retarding the latter upon operation of said safety brake mechanism. I

2. In an elevator installation, a hatchway,

, a body movable in said hatchway, guide rails for said movable body, a bufier carried by said movable body, said buffer comprising a cylinder, and a plunger secured to said body and movable in said cylinder, safety brakes carried by said buffer cylinder and adapted upon operation togrip said rails during descent of said body to stop movement of said cylinder, thereby causing the descent of said body to be retarded and finally stopped as the plunger moves in said cylinder, means for causing the operation of said safety brakes, and resilient means surrounding a'portion of said bulfer and mounted between said bulfer and said safety brakes for cuisl'iioning said bulfer upon operation of said safety brakes.

' 3. In an elevator installation, a hatchway,

a body movable in said hatchway, guide rails for said movable body, a buffer carried by said movable body, said buffer comprising a cylinder, fluid in said cylinder, and a. plunger secured to said body and movable in saidcylinder, means carried by said buffer and adapted, upon operation, to grip said operation of said gripping means, and a. spring surrounding said cylinder and mounted between a portion of said cylinder and said gripping means for retardmg the descent of said cylinder upon operation of said gripping means.

4. In an elevator installation, a hatchway, a body movable in said hatchway, guide rails for said body, a buffer carried by said movable body, said bufier comprising, a cylinder, and a plunger secured to said body and movable in said cylinder, safety brake mechanism, a support for said safety brake mechanism, said support being carried by said body, and said safety brake mechanism being adapted upon operation to rip the guide rails during the descent of said body to stop the descent of said support, means for causing the operation of. said safety brake mechanism, and resilient means between said support and a portion of said cylinder to retard and finally stop the descent of said cylinder when said support isbrought to a stopby said safety brake mechanism, said plunger a cylinder for said plunger, said cylinder be ing suspended from said body, fluid in said cylinder, safety brake mechanism for said body, a support for said safety brake mecha-,

nism, said support being carried by said bufier cylinder, and said safety brake mechanism being adapted upon operation to grip said rails during the descent of said body to stop the descent of said support, resilient means acting between said support and a portion of said bufier cylinder to retard and finally stop the descent of said cylinderwhen said support is brought to a stop by said safety brake mechanism, said. plunger being thereafter forced into said cylinder as said body continues'to descend to cooperate with the fluid therein to retard the descent of said body and finally bring it to rest, and-means for causing the operation of said safety brake mechanism.

6. In an elevator installation, a'hatchway, a movable body in said hatchway, guide rails for said body, a plunger secured to said body, a non-compressible liquid containing cylinder for said plunger, said cylinder be-- ing suspended from said bod and having upper and lower chambers, safety brake mechanism 'comprising safety blocks, provided with slots into which said guide rails extend, one side of each slot being formed with a cam surface, safety rolls carried by said safety blocks between said cam surfaces and said guiderails, lift rods for saidsafety rolls operable to wedge safety rolls between said cam surfaces and guide rails, a support for said safety brake mechanism, said support being carried by said buffer cylinder, means operable to cause the operation of said lift rods to wedge said safety rolls between said cam surfaces and guide rails during the descent of said body to stop the descent of said support, a spring between said support and a portion of said buffer cylinder to retard and finally stop the descent of said cylinder when said support is brought to a stop by said safety brake mechanism,-said plunger thereafter descending in said cylinder, and means for causing the liquid in said cylinder to be displaced from said lower chamber into said upper chamber by said plunger during its descent in said cylinder in such manner as to gradually retard the descending body and finallybring it to rest.

7. In an elevator installation a hatchway,

a movable body in said hatchway, guide rails for said body, a plunger secured to said body, a non-compressible liquid containing cylinder for said plunger, said cylinder having upper and lower chambers, rods adapted to suspend said cylinder from said body and to guide said plunger for movement in said cylinder, interconnected channel members and safety beams carried by said cylinder, a com-- pression spring mounted between a portion of said cylinder and said channel members, safety blocks carried by said safet beams, said safety blocks being provided with slots into which said guide rails extend, one side of each slot being formed with a cam surface, safety rolls carried by said safety blocks between said cam surfaces andsaid guide rails, lift rods for said safety rolls, said lift rods being provided with cam slots, pins carried by said safety blocks adapted to cooperate with said cam slots to move said lift rods toward said guide rails to wedge safety rolls between said cam surfaces and guide rails, rock shafts connected to said lift rods, said rock shafts being connected for simultaneous movement, a lever mounted on one of said rock shafts, a cable connected to said lever, a speed controlled governor adapted to be operated by said cable in response to the speed of operation of said body, means operable by said governor when said body is descending exceeds a predetermined speed to engage said cable to cause said cable to effect operation of said lever to cause said safety rolls to be wedged b ween said cam surfaces and guide rails to stop the descent of said-safety beams, said spring thereupon retarding and stopping the desecent of'said cylinder, and said plunger thereafter descending in said cylinder, and means for causing the liquid in said cylinder to be displaced from said lower chamber into said upper chamber by said plunger during its desecent in said cylinder in such manner as to gradually retard name to this specification.

ALEXANDER MARKS. 

